Admon is a system monitoring application. It is based on Zabbix, and is an enhanced version with many adjustments. Admon tries to make Zabbix as simple, smart, and easy to understand as possible, and it focuses on optimization of the alerting subsystem and data storage.

System Watchdog is a program that is designed to monitor a collection of Linux systems. It is configured to collect data on each monitored system at 5-minute intervals and build historical graphs using RRDTool. By default, it will gather statistics on CPU, memory, disk, and network usage. It also will attempt to monitor temperature and power settings. System Watchdog uses the paramiko module to ssh to all monitored systems. To access monitored systems, threads are implemented to access each remote host. After all threads have completed, watchdog will build a summary landing page to display the current status of each host, with links to a hardware inventory and resource graphs of each host.

The System Status Dashboard (SSD) is a status dashboard designed to provide an easy to understand view into an organization's infrastructure health status. It is modeled after status dashboard services like Google's App Status and Amazon's Service Health Dashboard and displays a matrix of services, dates, and their corresponding status in an easy to read calendar view. Services can be Web sites, APIs, internal IT systems, or anything else about which your users or customers require timely status information. It allows system administrators to easily create and track incidents and provides an excellent historical reference for SLA performance calculations.

Osmius is a monitoring tool for everything connected to a network. It features very high performance. It allows you to create and integrate business services, SLAs, and ITIL processes such as availability management and capacity planning. Osmius offers real GIS capabilities, BI, and data mining to keep track of SLA requirements.

Sentinella is a desktop application that monitors your system activity and, when a condition is met, takes the action that you've chosen. While monitoring your CPU, memory, hard drive, and network usage, Sentinella can be programmed to take specific actions when setpoints for utilization or time are met. It can power off, reboot, or hibernate your system, kill an active process, throw an alarm, or execute any command. Sentinella integrates perfectly with the main desktop enviroments (KDE, GNOME, XFCE, and others) and works under many Unix systems.

MOTDstat (Message Of The Day - System Status) will dynamically generate the /etc/motd file with current information about system status and usage. Using crontab, the script will periodically display the status of system resources and services. The original message of the day will be stored in the /etc/motd.orig file.
Configuring an email address, you'll receive notifications about the following issues with configurable warning and critical limits: high CPU load, exceeding disk space, intensive usage of swap space, a specific process or network service not running, NTP not synchronized, and too many messages in the mail queue.

Nagios has been around for quite some time, but producing output it can consume is something of a black art. Only the plugin documentation actually explains what all the extra semicolons or extended formatting even mean. This is especially onerous when performance consuming add-ons expect a specific structure before operating properly. The NagAconda package strives to greatly simplify the process of actually generating Nagios output using Python.

DTPSTree shows the running processes as a tree. It is a reimplementation of pstree from PSmisc for FreeBSD. It also works without /proc and will show the full set of processes in a jail even if init is not present.

Python System Monitor (Psymon) is a cross-platform task and performance monitor. It features global process monitoring, system load history (CPU, memory, network, and disks), disk information, network connections, detailed information and CPU, and memory percentage history per process.